Note 5 - Fair Value of Financial Instruments (Tables)

6 Months Ended

Sep. 30, 2021

Notes Tables

Investments Classified by Contractual Maturity Date [Table Text Block]

Total		<1 Year		1–3 Years		3–5 Years
$	60,647,982	$	33,103,514	$	17,237,693	$	10,306,775

Fair Value, Assets Measured on Recurring Basis [Table Text Block]

	As of September 30, 2021						As of March 31, 2021
	Level 1		Level 2		Total		Level 1		Level 2		Total
Money market funds	$	10,442,555	$	-	$	10,442,555	$	10,143,196	$	-	$	10,143,196
Corporate bonds		-		50,205,427		50,205,427		-		54,717,626		54,717,626
Total	$	10,442,555	$	50,205,427	$	60,647,982	$	10,143,196	$	54,717,626	$	64,860,822

Schedule of Available-for-sale Securities Reconciliation [Table Text Block]

	As of September 30, 2021									As of March 31, 2021
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value		Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Money market funds	$	10,442,555	$	-	$	-		$	10,442,555	$	10,143,196	$	-	$	-		$	10,143,196
Corporate bonds		49,163,545		1,152,671		(110,789	)		50,205,427		53,308,105		1,570,195		(160,674	)		54,717,626
Total	$	59,606,100	$	1,152,671	$	(110,789	)	$	60,647,982	$	63,451,301	$	1,570,195	$	(160,674	)	$	64,860,822

Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table Text Block]

	Less Than 12 Months					12 Months or Greater				Total
	Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses		Estimated Fair Value		Gross Unrealized Holding Losses
As of September 30, 2021
Corporate bonds	$	10,306,776	$	(110,789	)	$	-	$	-	$	10,306,776	$	(110,789	)
Total	$	10,306,776	$	(110,789	)	$	-	$	-	$	10,306,776	$	(110,789	)
As of March 31, 2021
Corporate bonds	$	10,322,539	$	(160,674	)	$	-	$	-	$	10,322,539	$	(160,674	)
Total	$	10,322,539	$	(160,674	)	$	-	$	-	$	10,322,539	$	(160,674	)